The implementation of CNC machine tools has greatly increased the productivity of metal cutting processes, and greatly increased the precision and complexity of parts that may be manufactured. The ability to manufacture parts under computer control has also significantly decreased the need for continuous operator supervision, and allowed one operator to manage a number of machines simultaneously. In some cases, machining operations are largely unattended. However, such efficiencies are strongly limited by chip control issues, especially in turning and boring applications. A common problem in the automation of these applications is the production of continuous, unbroken chips. These long, stringy chips tend to lead to tangles around the tool and workpiece, potentially damaging both the part and machine. This problem is largely unpredictable, and, currently, operator intervention is required to avoid and/or remove such tangles, potentially endangering the safety of the operator. This is especially problematic when dealing with difficult to machine and/or dangerous materials, such as pyrophoric and radioactive materials that must be machined under fluids, in gloveboxes, etc. In addition, large piles of tangled chips pose a disposal problem.
Various solutions have attempted to combat this problem and promote chip breaking, including modifying the geometry of the cutting tool, using external fixtures to vibrate the cutting tool, and using high pressure cooling systems to blast chips away. The use of special cutting tool geometries creates stresses in the chips, causing them to break. However, these solutions are unreliable, especially in finish turning applications, due to the resultant chips' flexibility. Current analytical and empirical models are predictively insufficient, and the use of special cutting tool geometries is, essentially, trial and error. It is common that a chip breaker design that is very effective for one turning application is completely ineffective for another, very similar, turning application. Disadvantageously, the solutions tend to be part geometry and material specific. The use of external devices retrofitted to the existing cutting tool to mechanically oscillate the cutting tool tip in and out of the cut in the feed direction is feasible, but problematic. This solution only works when machining an external part geometry that is aligned with the axes of the machine (e.g., an outer diameter or a face) and does not permit the fabrication of either outer or inner contour surfaces. It also fails to synchronize the oscillation of the cutting tool tip with the spindle speed (sometimes resulting in a continuous chip), it consumes workspace, and it reduces the stiffness of the cutting process, resulting in a poor quality surface finish. The use of a high pressure coolant stream directed at the tool-chip interface is only viable for processes with stable chip formation, and has limited effectiveness in contour turning applications with a complex moving tool-chip interface.
What is still needed in the art, however, are methods and systems in which toolpaths are chosen dynamically or non-dynamically, responsive to the cutting conditions present such that short chips are created. Preferably, these methods and systems may be utilized in turning applications, boring applications, as well as others.